Now, welfare. It's been suggested (by me) that people deserve a basic level of income proportional, to some extent, to their needs and life projects. It follows from this that those with more children will generally need and receive more income. However, it has been suggested to me several times that this might encourage having more children as a way to profit without "doing any work". Putting aside the question of whether having children, even children one ignores, qualifies as "work", it seems to me there is a simple solution to the problem. If having more children becomes a means to an unjust end (undeserved income), then the means should be removed. Enforced sterilzation is a bit Gestapo for my tastes, but I see no reason why children who are being created solely to generate income should not be taken, and the income attendant upon them redistributed, to the thousands of families who genuinely want more children.
(As an odd aside, removing the incentive to have "kids for cash" might also increase the use of birth control, thus reducing the problem of unwanted children and decreasing the STD rate.) The point is not to come up with a workable policy -- I'm glossing over more messy details than I can conveniently count; however, I do wonder why it would be bad to remove children from parents who cannot or will not care for them. There seems to be a very strong presumption in favour of keeping children with birth parents. And, if it leads to social problems (such as the "kids for cash" problem sketched above), should the presumption be, at some point, defeated?